using the Lee (or any) crimp on reloading 338LM

[cali_tz]

I had to get myself a Lee crimp for reloading solids like the Barnes TTSX on my 308 (California Condor zone for hunters requires lead free ammo).

Reading thru the manual for the die, Lee said that crimping (better) equalizes the 'start' pressure of the cartridge burn cycle, leading to much more even MVs.

MV variation is definitely something I need improvement upon with my 338LM, despite weighing each round to 0.1 grain, which is one kernel of N570.

Do you all agree with this claim by Lee? I would love to find out that crimping the neck provides a more even MV. Be an easy fix.

p.s. I am using lapua 338LM brass.

 

[armorpl8chikn]

Re: using the Lee (or any) crimp on reloading 338LM

Let me put it this way. If I have made a tool that you need, when you see what it does, <span style="text-decoration: underline">you</span> will be able to determine if it is something you need. If I have to make some "claim", then there may be some question whether you need the tool and I need to convince you to buy this wonderful magic thing.
Bottom line. The Lee factory crimp die will put great crimps on your ammo. If I am shooting a lever action, an extremely heavy recoiling bolt action(think elephant rig),a heavy recoiling revolver, and POSSIBLY a semi auto, then I may want to crimp for safety. If a semi auto feeds correctly then any ammo with proper neck tension doesn't need a crimp either.

No a crimp does not improve your powder burning efficiency. To put it another way: it is not magic fairy dust that make poor reloads perform. If your reloading is good you only need a crimp in special circumstances.

 

[X-fan]

Re: using the Lee (or any) crimp on reloading 338LM

Let me keep it plain.
Don't waste your money or fk up your accuracy in the process.


The 16 pound 338L recoils at 10fps boots you with 25ftlbs.
My light (8 pound) 416 recoils at 29fps and hammers you with 104ftlbs.
The Lapua is a gentle bump while the 416 is like being hit by a sledge hammer.
I don't crimp my 416 so you don't need to crimp the puny Lapua.

Hope that helps paint an understanding

 

[cali_tz]

Re: using the Lee (or any) crimp on reloading 338LM

I was not intending for the crimp on the 338LM to deal with recoil, but more to more uniformly implement neck tension for purposes of uniform pressure build up leading to more consistent shot to shot MVs.

Puny lapua indeed ...

 

[armorpl8chikn]

Re: using the Lee (or any) crimp on reloading 338LM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cali_tz</div><div class="ubbcode-body">I was not intending for the crimp on the 338LM to deal with recoil, but more to more uniformly implement neck tension for purposes of uniform pressure build up leading to more consistent shot to shot MVs.

Puny lapua indeed ...

</div></div>

OK let me make it even more plain. Don't waste your money.

 

[ChrisGarrett]

Re: using the Lee (or any) crimp on reloading 338LM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cali_tz</div><div class="ubbcode-body">I was not intending for the crimp on the 338LM to deal with recoil, but more to more uniformly implement neck tension for purposes of uniform pressure build up leading to more consistent shot to shot MVs.

Puny lapua indeed ...

</div></div>

Not needed.

If you want to control neck tension, anneal your cases and use bushing dies of one flavor, or the other.

I got a Lee Factory Crimp Die years ago for my 7RM and used it once. I prefer going with taper crimps, if I'm going to crimp at all and I don't 99% of the time.

Chris

 

[cali_tz]

Re: using the Lee (or any) crimp on reloading 338LM

Chris, yes my brass is annealed, and I do use Redding Comp S bushing die.

Just curious why did you stop using the Lee for your 7RM... was there a problem that arose or you just didn't see any benefit.

 

[ChrisGarrett]

Re: using the Lee (or any) crimp on reloading 338LM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cali_tz</div><div class="ubbcode-body">Chris, yes my brass is annealed, and I do use Redding Comp S bushing die.

Just curious why did you stop using the Lee for your 7RM... was there a problem that arose or you just didn't see any benefit. </div></div>

I don't really crimp any longer. Some guys have noticed better groups with crimped ammo, but that could just be the bullets hitting a higher node, due to the added pressure (velocity) that the crimp creates.

A few extra grains of powder might do the same thing and you're not dicking around with having to have brass trimmed perfectly, potentially collapsing your shoulders and the like.

I pretty much use bushing dies, either neck, or FL, now. I don't even crimp my 223 loads for my AR15s, as my initial FL sizer put a good .004" of tension on the brands of cases I loaded and I got no setback.

IIRC, the Lee FCD applies the crimp in sections, unlike a taper crimp die, which places the crimp at the edge around the entire neck. If I'm going to crimp, I'm going with the tapers, but I'm no expert and I haven't done much testing on the matter, so who knows?

Chris

 

[cali_tz]

Re: using the Lee (or any) crimp on reloading 338LM

honest answers... thanks Chris. I guess I'll hold off for now. The Lee die for 338LM is expensive and requires another press since it's not the std 7/8-14 die size. So it's like a $250 proposition all told for me to add. I'd pay that if I knew it would tighten my groups by 50%, if only by making MV's more consistent. That's my single biggest issue after the wind variable.

 

[ChrisGarrett]

Re: using the Lee (or any) crimp on reloading 338LM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cali_tz</div><div class="ubbcode-body">honest answers... thanks Chris. I guess I'll hold off for now. The Lee die for 338LM is expensive and requires another press since it's not the std 7/8-14 die size. So it's like a $250 proposition all told for me to add. I'd pay that if I knew it would tighten my groups by 50%, if only by making MV's more consistent. That's my single biggest issue after the wind variable. </div></div>

Yeah, if, if, if...

The 338LM cartridge was designed from the onset, to be a long range sniper cartridge and as is, it's an inherently accurate round, therefore, it doesn't require a crimp to shoot well.

Prep your brass well, watch your powder charges, anneal, turn necks if you have to and watch for excessive runout.

Also, standard deviations are often lowered by filling the case with more gun powder. Nosler is a big proponent of high volume powders, so stuff with a lower density, but which takes up more case space often yields a more consistent velocity from shot to shot, than a high density, low volume powder.

Spend your time out shooting and practicing your aim.

Chris

 

[cali_tz]

Re: using the Lee (or any) crimp on reloading 338LM

Yes I've heard the stuffing the case with powder advice ... it seems to reduce MV variations with the N570 and 250 Scenar where you can literally fill the case with powder in fact I am pretty sure powder is fully being burned in this case, based on my ladder results.

But you can't do that with the 300 Scenar. WIth any powder that I am aware of.

Spending time shooting and practicing is fine. But I'm to the point where aim is not the issue. The issue, at 1500 yards plus now is wind (depending on amount of course) as the primary variable creating dispersion, then MV variation creating dispersion. Powder is being weighted to the kernel. I am not measuring case volumes so that could be a culprit potentially, but I am trusting that Lapua does a good job on that, at the price it sells for.

 

[ChrisGarrett]

Re: using the Lee (or any) crimp on reloading 338LM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cali_tz</div><div class="ubbcode-body">Yes I've heard the stuffing the case with powder advice ... it seems to reduce MV variations with the N570 and 250 Scenar where you can literally fill the case with powder in fact I am pretty sure powder is fully being burned in this case, based on my ladder results.

But you can't do that with the 300 Scenar. WIth any powder that I am aware of.

Spending time shooting and practicing is fine. But I'm to the point where aim is not the issue. The issue, at 1500 yards plus now is wind (depending on amount of course) as the primary variable creating dispersion, then MV variation creating dispersion. Powder is being weighted to the kernel. I am not measuring case volumes so that could be a culprit potentially, but I am trusting that Lapua does a good job on that, at the price it sells for.
</div></div>

You don't say, but what kind of SDs and extreme spreads are you typically seeing and what size is the population.

The Berger 250s that I tested the other day had SDs of 21/22 with ESes of 60, for strings of 10, with the particular load I used--88.5grs of H-4831sc. I seated ultra long, so there was a lot of space in the cases.

They weren't great, but I was at 100 yds, so no biggie. I've gotten some combos down to single digits, but if I'm at an SD of 10-15 for 10 shots, I'm happy.

Of course, the longest I get to shoot is 1000 yards.

Chris

 

[cali_tz]

Re: using the Lee (or any) crimp on reloading 338LM

Sorry I meant to say that with my fully stuffed (98.8 gr of N570) cases with the 250 Scenar, that the powder is NOT being fully burned, there is so much.

My samples size is typically between 5 and 10. 10 is obviously better statistically but budgets are not unlimited on time/money. My numbers are quite comparable to yours, low to mid teens on SD. For good first hit performance though out past 1500 yards, one needs 2 SD's (95% confidence) to provide like 5fps variance.

I don't get too wrapped around the axle on this, since in our area of California, canyon winds are so variable that even if we master the vertical variations due to ammo build, the wind at a mile distance is going to throw everyones shot off target randomly, no matter how good they are. Bullet BC's can mitigate, but they can't auto correct for shifting winds.

 

[ChrisGarrett]

Re: using the Lee (or any) crimp on reloading 338LM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cali_tz</div><div class="ubbcode-body"><span style="color: #000099">Sorry I meant to say that with my fully stuffed (98.8 gr of N570) cases with the 250 Scenar, that the powder is NOT being fully burned, there is so much. </span>My samples size is typically between 5 and 10. 10 is obviously better statistically but budgets are not unlimited on time/money. My numbers are quite comparable to yours, low to mid teens on SD. For good first hit performance though out past 1500 yards, one needs 2 SD's (95% confidence) to provide like 5fps variance.

I don't get too wrapped around the axle on this, since in our area of California, canyon winds are so variable that even if we master the vertical variations due to ammo build, the wind at a mile distance is going to throw everyones shot off target randomly, no matter how good they are. Bullet BC's can mitigate, but they can't auto correct for shifting winds. </div></div>

My '06 VV pamphlet shows 98.8 of N-570, as being FULL, so I might back that off a bit, if you care.

What primers are you using? I'm pretty much stuck on 215Ms, but have used 215s and WLRP Magnums in the past.

It's all 'the thrill of the chase' for me, but at some point, tinkering needs to subside and I need to go with what I have.

Take care, Chris

 

[cali_tz]

Re: using the Lee (or any) crimp on reloading 338LM

215Ms exclusively.

Yes 98.8 N570 is definitely FULL. I did use 98.6 98.4 etc for my ladder and it turns out 98.8 was no faster than 98.6.

Thrill of the chase is where the fun is, but one wants to see convergence towards ones goals. Light at the end of the tunnel.